Nightwing lays out his theory why the Raptor seems to hate Bruce Wayne, him and anybody he deems elite. Raptor failed to protect Nightwing’s mother as he promised by not following Boss Zucco and preventing him from tampering with the lines, leading to the Flying Graysons’ deaths. Instead, he followed Bruce Wayne, who attended the circus, to rob him.
Nightwing calls Raptor a thief, not a protector.
From – Nightwing Vol. 4 #32